To order this report, contact: U. S. Geological Survey Books and Open-File Reports Sales, PO Box 25425 Denver, CO. 80225, or call (303) 236-7476. There are two versions available:

OF 92-200-A is a 22-page paper version.

OF 92-200-B comes on a 3.5-in. Macintosh 1.4MB high-density diskette.

Requirements for the diskette version are: Apple Computer, Inc., HyperCard 2.0™ software, and an Apple Macintosh™ computer with High-Density drive. If you are using System 7, we recommend using at least 3 MB of RAM with 1.5 MB of system memory available for HyperCard.

Purchasers of the diskette version of this report, which includes all of the text and graphics, can use HyperCard 2.0 ™ software (not supplied) to change the model (by adding geologic patterns, symbols, colors, etc.) or to transfer the model to other graphics software packages.